Titanium carbide (TIC) composites, and tungsten carbide (WC) composites are well recognized for their resistance to wear, and general corrosion and resistance to softening at high temperature. Products of of widely varying nature and utility are made from them, and in many applications they serve very well. In many or most cases, the TiC composites function as well as WC composites and frequently cost and weigh less.
However, there are some applications which until this invention have have been better served by WC composites than by TiC composites. For example, previously-known TiC composites are not sufficiently resistant to erosion to be useful in applications such as valves, seals, and bearing surfaces, feed screws, concrete spraying and sandblasting nozzles which will be exposed to severely erosive fluids, particles, and fluid streams. Examples are encountered in, mining, geothermal drilling, and coal liquefication industries.
This field of applications has been primarily served by WC composites in which WC particles are sintered into a cobalt matrix. Even as to these, wherever hydrogen sulfide is likely to be encountered, such as in most deep hole drilling, the cobalt matrix is subject to severe chemical erosion, although that was accepted as an unavoidable circumstance, because there was no alternative.
Over the years conditions have changed. The supply of cobalt has become increasingly unreliable, and as a consequence increasingly expensive. This is because it mostly comes from the country of Zaire, whose social conditions are not conducive to reliability of mining and export operations. This combined with the high specific gravity and inferior erosion resistance (to some conditions) of WC--Co composites, has led the instant inventor to invent a new composite of lesser weight and cost, and with improved erosion resistance.
Lightness of weight becomes important when the composite is incorporated in a moving part. The lighter the composite is, the less energy is needed to move it in operation. The more resistant the composite is to erosion, the longer its life, and the longer the period will be between repair and replacement.
This invention provides a lighter weight composite with erosion resistance at least equivalent to cobalt/WC composites, it utilizes constituents which are readily available in the United States at normal prices. It also can utilize various matrices with high concentrations of TiC capable of being resistant to many chemical erosive conditions which may be damaging to WC/cobalt such as H.sub.2 S.